The feasibility of leaf reflectance-based taxonomic inventories and diversity assessments of species-rich grasslands: a cross-seasonal evaluation using waveband selection

Thornley, Rachael Helen; Verhoef, Anne; Gerard, France F.; White, Kevin. 2022 The feasibility of leaf reflectance-based taxonomic inventories and diversity assessments of species-rich grasslands: a cross-seasonal evaluation using waveband selection. Remote Sensing, 14 (10), 2310. 21, pp. 10.3390/rs14102310

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Abstract/Summary

Hyperspectral leaf-level reflectance data may enable the creation of taxonomic inventories and diversity assessments of grasslands, but little is known about the stability of species-specific spectral classes and discrimination models over the course of a growing season. Here, we present a cross-seasonal dataset of seventeen species that are common to a temperate, dry and nutrient-poor calcareous grassland, which spans thirteen sampling dates, a week apart, during the spring and summer months. By using a classification model that incorporated waveband selection (a sparse partial least squares discriminant analysis), most species could be classified, irrespective of the sampling date. However, between 42 and 95% of the available spectral information was required to obtain these results, depending on the date and model run. Feature selection was consistent across time for 70 out of 720 wavebands and reflectance around 1410 nm, representing water features, contributed the most to the discrimination. Model transferability was higher between neighbouring sampling dates and improved after the “green-up” period. Some species were consistently easy to classify, irrespective of time point, when using up to six latent variables, which represented about 99% of the total spectral variance, whereas other species required many latent variables, which represented very small spectral differences. We concluded that it did seem possible to create reliable taxonomic inventories for combinations of certain grassland species, irrespective of sampling date, and that the reason for this could lie in their distinctive morphological and/or biochemical leaf traits. Model transferability, however, was limited across dates and cross-seasonal sampling that captures leaf development would probably be necessary to create a predictive framework for the taxonomic monitoring of grasslands. In addition, most variance in the leaf reflectance within this system was driven by a subset of species and this finding implies challenges for the application of spectral variance in the estimation of biodiversity.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.3390/rs14102310
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	2072-4292
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
Additional Keywords:	semi-natural grasslands, biodiversity, hyperspectral, species classification, multi-temporal, partial least squares discriminate analysis, spectral variation hypothesis (SVH)
NORA Subject Terms:	Ecology and Environment
Date made live:	25 Jul 2022 16:03 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/532980

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